Filter "image stabilizer"

[guju]

Recently I discovered this new filter.
What I miss is an explanation of the params Smoothing and Gravity.
The long green bar seems to be the amount of shaking?
And what does the field at its end mean?

Since long I used VirtualDub2.
Sadly its author (the honoured shekh - may the hair on his toes never fall out!)
seems to have quit dev, so it will get more and more outdated
(not to talk about its numerous bugs and outdated architecture).
However when it's about deshaking movies to my opinion it does best,
in conjunction with the so-called
"Lens Transform tool" (https://forum.doom9.org/showthread.php?p=1747268) and
"Deshaker" filter (https://www.guthspot.se/video/deshaker.htm)

"Deshaker" allows many important settings; without them
stabilizing doesn't produce usable results.

But for many movies it still produces bad results:
when the "field of view" (FOV) is larger than say 20 degrees,
which is probably in most of the cases.
Only for super-super tele movies you get acceptable results.
Stabilizing wide-angle movies worsens them, as they get "wobbling",
you get sea-sick.
The "lens transform tool" (its name is misleading for stabilizing)
helps very much at those cases. (Still you loose params from DeShaker).

The simple method your filter seems to use produces acceptable results
ONLY in very few cases:
- low FOV,
- small shaking,
- no kind of logos etc.

I fear that many users might use it not only for those cases,
adding movies to all those bad existing stabilized movies I have seen.

Please take this as it is meant - as constructive feedback - will you? 

[szlldm]

Smoothing: filtering strength. higher value means more deshaking, but also more drift
Gravity: the amount of "force" that pulls back the drifted image to the center
The long bar, with the green(?) rectangle at the end creates the indicator for the scene change detector. The scene change detector threshold is set by the Scene threshold slider. The bar below that indicate the scene change detector output value. The green(?) rectangle at the end imitates an LED, so it flash when scene change detector output exceeds the threshold.